1. Field of the Invention
The present invention relates generally to a magnetic head, and more particularly, to a magnetic head that supports a magnetic head unit by a slider.
2. Description of the Related Art
Generally, an ordinary magnetic disk drive that uses a flexible magnetic disk having a coercive force of 900 oersted (Oe) or less as a magnetic recording medium allows a relatively low rotational speed of for example 300 rpm. In this case, magnetic recording and reproduction is performed by causing the magnetic head to be in direct sliding contact with the magnetic disk.
However, with advances in recent years in high-density recording on magnetic disks, the rotation speed of the magnetic disk has been increased to for example 3000 rpm, with the coercive force of the magnetic disk being increased to 1500 Oe or more. As a result, in order to accommodate such so-called high-capacity magnetic disks a magnetic disk drive has appeared in which the magnetic head is provided with a narrow gap. Hereinafter such a magnetic disk drive will be referred to as a high-capacity magnetic disk drive.
Since a high-capacity magnetic disk drive allows the magnetic disk to be rotated at high speeds, the magnetic disk and the magnetic head used therein may be easily damaged if the magnetic head were to be caused to be in direct contact with the magnetic disk, as is done in the conventional magnetic disk drive.
As a result, the high-capacity magnetic disk drive is designed so that the magnetic head floats in an elevated state over the surface of the high-capacity magnetic disk due to an elevating force arising as a result of a change in an air flow caused by a relative speed between a slider surface of the magnetic head and the magnetic disk. Magnetic recording and reproduction is performed while a state of non-contact between the magnetic head and the magnetic disk is maintained.
Further, in recent years a so-called compatible-type magnetic disk drive has emerged, having a configuration in which magnetic recording and reproduction of an ordinary magnetic disk and a high-capacity magnetic disk are performed with a single magnetic disk drive. Hereinafter such a magnetic disk drive is referred to as a compatible magnetic disk drive. The compatible magnetic disk drive enables an improvement in versatility because it can be used with both ordinary magnetic disks and high-capacity magnetic disks.
Additionally, the magnetic head mounted on the compatible magnetic disk drive has both an ordinary magnetic head unit for accommodating ordinary magnetic disks and a high-capacity magnetic head unit for accommodating high-capacity magnetic disks. More specifically, each magnetic head unit is disposed on a slider made, for example, from ceramics or the like, with a central groove for flotation formed on the slider and each one of the magnetic head units being selectively positioned on either side of the central groove so as to sandwich the central groove between the magnetic head units.
In particular, the ordinary magnetic head unit has a wide gap compared to the high-capacity magnetic head unit and so is given a bulk-type head structure, with the magnetic head unit being stuck between the slider body and the panel-shaped slider side portion which together form the slider using an epoxy-type adhesive, thereby fixedly mounting the magnetic head unit on the slider.
However, with the above-described conventional magnetic head, in which the ordinary magnetic head unit is attached using an epoxy-type adhesive between the slider body and the slider side panel which together form the slider, the coefficient of thermal expansion of the epoxy resin after hardening is high. As a result, in the operating temperature range of the compatible magnetic disk drive mounting a magnetic head a slight deformation occurs in the shape of the sliding contact surface on the side on which the ordinary magnetic head unit is positioned.
That is, particularly at the higher end of the operating temperature range of the compatible magnetic disk drive, the epoxy resin thermally expands. This thermal expansion causes the epoxy resin to protrude above the surface that is in sliding contact with an ordinary magnetic disk, or, alternatively, causes a difference in level to appear between the ordinary magnetic head unit and the slider, that is, the slider body and the slider side portion. If the condition of the surface that is in sliding contact with a magnetic disk deteriorates, then the ordinary magnetic disk might be damaged during magnetic recording and reproduction and optimum magnetic recording and reproduction might not be performed.
It should be noted that the above-described disadvantage is a particularly troublesome problem for positioning an ordinary magnetic head unit performing magnetic recording and reproduction in a state in which the magnetic head is in sliding contact with the magnetic disk.
Accordingly, it is a general object of the present invention to provide an improved and useful magnetic head and structure for supporting same, in which the disadvantages described above are eliminated.
The above-described object of the present invention is achieved by a magnetic head comprising:
a first magnetic head unit for recording to and reproducing from a first flexible rotating recording medium;
a second magnetic head unit for recording to and reproducing from a second flexible rotating recording medium having a coercive force lower than a coercive force of the first flexible rotating recording medium; and
a slider supporting the first and second magnetic head units,
the second magnetic head unit being attached to the slider using an adhesive, the adhesive including a filler so as to substantially match a coefficient of thermal expansion of the adhesive to a coefficient of thermal expansion of the slider.
According to the invention described above, the adhesive can be restrained from projecting into or retreating from the sliding contact surface and the formation of a difference in level between the second magnetic head unit and the slider can be suppressed even when the ambient temperature at which the magnetic head is being used rises, because the coefficient of thermal expansion at the adhesive is substantially the same as the coefficient of thermal expansion of the slider. As a result, the occurrence of damage to the recording medium can be prevented and reliably stable magnetic recording and reproduction can be achieved.
Additionally, the above-described object of the present invention is also achieved by a magnetic head comprising:
a first magnetic head unit for recording to and reproducing from a first flexible rotating recording medium;
a second magnetic head unit for recording to and reproducing from a second flexible rotating recording medium having a coercive force lower than a coercive force of the first flexible rotating recording medium; and
a slider supporting the first and second magnetic head units,
the second magnetic head unit being attached to the slider using an adhesive, the adhesive including a filler at a rate of 50 through 80 percent by weight.
According to the invention described above, the coefficient of thermal expansion of the adhesive as a whole including the filler can be reduced.
Accordingly, the coefficient of thermal expansion at the adhesive can be restrained even when the ambient temperature at which the magnetic head is being used rises, and the formation of a difference in level between the second magnetic head unit and the slider can be suppressed. As a result, the occurrence of damage to the recording medium can be prevented and reliably stable magnetic recording and reproduction can be achieved.
Additionally, the above-described object of the present invention is also achieved by the magnetic head as described above, wherein the filler is made of a material having a coefficient of thermal expansion lower than the coefficient of thermal expansion of the adhesive.
According to the invention described above, the coefficient of thermal expansion of the adhesive as a whole including the filler can be reliably reduced because the filler acts to inhibit thermal expansion of the adhesive even as the ambient temperature rises and the adhesive attempts to expand.
Additionally, the above-described object of the present invention is also achieved by the magnetic head as described above, wherein the filler comprises substantially spherical particles having a diameter of 1 xcexcm or less.
According to the invention described above, the second magnetic head unit can be attached to the slider in an optimum state despite the inclusion of filler in the adhesive.
In other words, it is desirable that the thickness of the adhesive be the minimum amount necessary to fixedly mount the second magnetic head unit on the slider. More specifically, it is desirable that the thickness of the adhesive be 1 xcexcm or less.
Accordingly, the thickness of the adhesive existing between the second magnetic head unit and the slider can be made to be 1 xcexcm or less despite the inclusion of filler in the adhesive, and the stability and reliability of the magnetic head can be improved.
Additionally, the above-described object of the present invention is also achieved by a method of manufacturing a magnetic head comprising the steps of:
(a) mounting a first magnetic head unit for recording to and reproducing from a first flexible rotating recording medium; and
(b) mounting a second magnetic head unit for recording to and reproducing from a second flexible rotating recording medium having a coercive force lower than a coercive force of the first flexible rotating recording medium,
the step (b) of mounting the second magnetic head unit comprising the steps of:
positioning the second magnetic head unit between a slider body and a slider side panel that together form the slider so that a gap of 1 xcexcm or less is formed between the second magnetic head unit and the slider body and a gap of 1 xcexcm or less is formed between the second magnetic head unit and the slider side panel; and
introducing into each of the gaps an adhesive material containing both filler comprising particles having a diameter exceeding 1 xcexcm and filler comprising particles having a diameter of 1 xcexcm or less, using the gaps as a filter such that only the filler comprising particles having a diameter of 1 xcexcm or less together with the adhesive material fill the gaps.
According to the invention described above, the gaps function as a filter when introducing the adhesive therein.
As a result, of the filler particles of various size only those having a diameter of 1 xcexcm or less, that is, the width of the gaps, are loaded into the gaps together with the adhesive. Accordingly, the thickness of the adhesive inserted between the second magnetic head unit and the slider can be easily and reliably kept to 1 xcexcm or less.